The present invention relates to a hypermedia system in a network environment, and more particularly to a hypermedia system intensively managing secondary information which is based upon directory information and directory data originating from a node link structure in a directory server in a network.
Recently, hypermedia systems have been drawing much attention as a technology for managing computer information.
A hypermedia system is used to process multimedia data including image data, voice data, and text data based upon a hypertext structure that permits retrieval in an interactive manner without using file names, by directly relating the contents of related data files. The data files hereafter will be called nodes.
The World Wide Web (hereinafter called WWW) is an example of widely used hypermedia systems in a network environment. FIG. 13 shows this type of conventional hypermedia system structure.
As shown in FIG. 13, WWW comprises client 131 and WWW servers 132a, 132b, and 132c. Each of WWW servers 132a, 132b, 132c stores several content files as nodes in hypertext. The location of these contents are uniquely determined by a node identifier called URL (Uniform Resource Locator) . The relation between nodes is described by tracking the URL described in each content file. Solid arrows in FIG. 13 show data flows, while dotted arrows indicate relations between nodes.
Client 131 accesses WWW server 132a in a network according to the URL designated by a user, obtains a content file 1321 of a node identified by the node identifier, and outputs its content. For example FIG. 13 indicates, a case where a node identifier is designated in the content file 1321 of server 132a. Client 131 obtains a content file 1321 from server 132a and outputs its content (such as text) in a display screen. Anchor area 1311 is defined in the content file 1321 which is displayed, and when the area makes a selection, a node identifier of the content file 1322 linked to content file 1321, is determined. Client 131 then accesses the server 132c in a network 130 to obtain and output the content of 1322.
Further, Japanese Patent Application No. Hei. 8-023319 ("Hypertext System") discloses a technology to make the process of navigation more effective by recognizing the content of the content files and the status of their relations in such a way that directory servers can manage node data such as indexes which indicate the content of the content files, the node identifier of the content files, and the link data in a network. This technology allows for the concentration of content files scattered in a network to be centralized in one location.
Another conventional system is disclosed in Martijn Koster's paper "ALIWEB" in Computer Networks and ISDN Systems, pp. 175-182.
According to the above-mentioned conventional hypermedia system however, it is impossible to see the link data of the nodes or its contents until the client reads the content of the nodes on the WWW.
Further, even in an approach demonstrated in Japanese Patent Application No. Hei.8-023319, due to a large amount of data on the WWW, results obtained from inquiries based on the content of content files and node link relations for directory service, proved the resulting information to be too vast. Unless the operation of retrieval and navigation is repeatedly performed, the target information is unable to be obtained.
In order to effectively navigate a large amount of node information existing in a network, secondary information about the macro structure is needed. Having this kind of knowledge enables one to browse node content as well as the hypermedia structure comprising node link data. However, the previously mentioned conventional technology permits navigation only based on primary information such as link structure or keyword indexes relating to each node.
Therefore, a first objective of this invention is to ensure more efficient navigation for users by using additional secondary information in a hypermedia system operating in a network environment.
In addition, when storing the secondary information used for navigation in a directory server, the secondary information must be updated as node information is generated and updated. This makes the workload heavy for a server manager.
Accordingly, a second objective of this invention is to provide a means to more effectively update the secondary information in a directory server.